One environment in which seals are utilized wherein end play may occur is that of the track of a track-type material handling vehicle. It is desirable to seal the space between the track pin and associated elements. One example of an improved track pin seal for such purposes is shown in U.S. Pat. No. 3,614,113 of Duane L. Burk, which patent is owned by the assignee hereof. In that patent, an improved spring washer structure is provided for urging an annular boot into sealing engagement with confronting track link structures. As pointed out in the Burk patent, extensive efforts have been made to provide suitable seals for such environments. However, the prior art seals have not proven completely satisfactory.